The present invention relates generally to image and optical systems, and more particularly to an optical system and to a method of making same.
Optical technologies and sciences have evolved from ancient observations and understandings of the nature of light to the manner in which light can be manipulated via one or more optical devices, such as through a lens or a combination of lenses. One characteristic usually important in optical technologies relates to resolution of an object. Resolution can be defined as the ability of an optical device to distinguish between small objects. In most conventional lens and imaging systems, resolution generally depends on a numerical aperture of a lens.
The numerical aperture is a parameter of a lens objective corresponding to its ability to gather light and resolve fine specimen detail at a fixed object distance. The numerical aperture is functionally related to the index of refraction of the imaging medium. For example, air has a refractive index of about 1.0. Thus, the refractive index of the imaging medium is a limiting factor in achieving numerical apertures greater than 1.0. Therefore, in order to obtain higher working numerical apertures, and, in turn, improved resolution, the refractive index of the medium between the front lens of the objective and the specimen can be increased to above 1.0 (e.g., to about 1.5). In order to increase the numerical aperture, oil immersion techniques have been developed, which require a physical image medium (e.g., water, glycerin, immersion oil, etc.) other than air.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
One aspect of the present invention relates to an optical system that includes an optical sensor having an array of light receptors having a pixel pitch. A lens optically associated with the optical sensor is configured with optical parameters functionally related to the pitch and a desired resolution of the optical system. As a result, the lens is operative to substantially map a portion of an object having the desired resolution along the optical path to an associated one of the light receptors.
Another aspect of the present invention relates to a method of designing an optical system. The method includes selecting a sensor with a plurality of light receptors having a pixel pitch. A desired minimum spot size resolution is selected for the system and a lens configured with optical parameters based on the pixel pitch and the desired minimum spot size is provided so as to map the plurality of light receptors to part of the image according to the desired resolution.
The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents. Other advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.